There is some evidence that a healthy diet rich in anti-oxidants and vitamins is good for asthma

Dr Mike Thomas, Aberdeen University

The study looked at five to 10-year-old schoolchildren in the Greenwich area of London, asking their parents about their child's fruit intake, and about any symptoms they had suffered.

While no link was found between apple juice consumption and a reduced chance of an actual asthma diagnosis, the link between wheezing and drinking the juice was quite strong.

The appearance of wheezing symptoms is one of the most important signs that a child is at increased risk of asthma, although many with the symptoms are not eventually diagnosed with the illness.

A similar, but weaker, benefit was found for children eating bananas at least once a day compared with less than once a month.

Cheaper solution

The apple juice involved did not have to be fresh apple juice - long-life juices made from concentrate were also effective.

Dr Peter Burney, who led the project, said that it was possible that 'phytochemicals' in apples, such as flavanoids and phenolic acids, were helping to calm the inflammation in the airways which is a key feature of both wheezing and asthma.

He said it wasn't clear why a link between eating apples themselves and reduced asthma symptoms - already spotted in other research in adults - did not appear among these children.

"Further studies are needed to confirm the protective effects of apple juice from concentrate and bananas," he said.

Dr Mike Thomas, an Asthma UK researcher at the University of Aberdeen, said that the study was further evidence of the protective effect of apples.

Research from the university published last week suggested that women who ate plenty of apples during pregnancy were protecting their unborn children against asthma later on.

He said: "There is some evidence that a healthy diet rich in anti-oxidants and vitamins is good for asthma.

"It is yet another reason why we should be encouraging a healthy diet."